1. Field of the Invention
The present invention relates generally to a navigational system and, more particularly, to a navigational system for exchanging positional information between a plurality of navigational systems.
2. Description of Background Art
When driving a plurality of vehicles as a group, the distances between the vehicles always change depending on the road situations and the needs of each driver. Therefore, it becomes a matter of concern for each driver whether the relative distance between the vehicles is within an easy reach or not for example, depending on picking up of the pace of one vehicle or slowing down of the pace of another. If the relative distance becomes too large, each driver must adjust the pace so as not to stray away from the group.
In order to satisfy such driver's needs as above, a capability of displaying the current position of a first vehicle and the current position of another vehicle on a map screen has been proposed as a part of a so-called party capability for example.
In recognizing the position of another vehicle by each driver in a group, it is most important for each driver to know the relative bearing or distance with other vehicles rather than knowing where the other vehicles are located on the map.
However, in the above-mentioned related art, only the current positions of a first vehicle and the other vehicles are displayed on a map screen, so that, in order to know the distance with any other member in a group, the actual distance must be computed on the basis of the distance and a display scale on the map display.